Showing papers in "International Journal of Oral & Maxillofacial Implants in 1992"

Failures and complications in 391 consecutively inserted fixed prostheses supported by Brånemark implants in edentulous jaws: a study of treatment from the time of prosthesis placement to the first annual checkup.

Abstract: A total of 391 edentulous maxillae and mandibles was consecutively treated with routine fixed prostheses, supported by 2,199 implants. The patients were followed for 1 year; the overall success rate was 99.5% and 98.1% for the prostheses and implants, respectively. The number of severe complications was low, but it was possible to identify a significantly higher ratio of problems in the maxillae throughout the observation period than for the mandibles. While many problems occurred in both the maxillae and mandibles, there were also problems more typical for each jaw. Diction and fractures of resin teeth were more common problems in maxillae; cheek and lip biting was a more frequent postinsertion complication in the treatment of mandibles. Most problems were easily resolved, and the retrievability of the prostheses was of great advantage.

Bone regeneration around titanium dental implants in dehisced defect sites: a clinical study.

Abstract: Insufficient bone volume can be a significant problem when placing dental implants. This clinical study was designed to evaluate bone regeneration potential at dehisced dental implant sites. Nineteen titanium dental implants with exposed threads were studied. To create a secluded space for bone formation, an expanded polytetrafluoroethylene (e-PTFE) membrane was placed over the exposed implant sites secured with an implant cover screw and completely covered with the flap. Three membranes perforated the overlying soft tissue during the healing time and were removed prematurely. The remaining membranes were removed after an uneventful healing period of 4.5 to 6 months. Fourteen of 19 dehisced implant sites were completely covered with newly formed bonelike tissue; 4 implants demonstrated partial bone fill at reentry and 1 implant showed partial fill with soft tissue. In five implant sites a reentry was performed between 6 and 9 weeks; nonmineralized fibrous tissue was found to fill the space under the membrane. At 16 of the 19 implant sites there were similar dehiscence-type defects that were evaluated as a group. These dehiscences varied from 2.0 to 9.0 mm. The percentage of bone fill at reentry ranged from 28.4% to 100% (mean 89.6%; SD 22.51; SE 5.63) and was highly significant (P < .0001). Six to 12 months after prosthesis connection, 12 of the 19 implants were available for radiographic interpretation and an average bone loss of 1.73 mm (SD = 0.43) was measured. This surgical application of an e-PTFE membrane suggested a viable clinical method for enhancing bone formation around dental implants.

Loads and designs of screw joints for single crowns supported by osseointegrated implants.

Abstract: The problem of screw stability was approached in this study by calculating the maximum occlusal forces in vivo for patients with single implant restorations (which use only one screw to secure the prosthetic reconstruction to the implant). The measurements of occlusal forces together with geometric parameters for the individual patients were used to determine the necessary holding capabilities of the screw joint. Different screw designs were tried in bench test situations and the results were compared with clinical situations. A gold alloy screw with a flat head and high tightening torque (35 Ncm) produced the best results.

Reconstruction of maxillary alveolar defects with mandibular symphysis grafts for dental implants: a preliminary procedural report.

Abstract: Partially edentulous patients with alveolar defects contraindicating implant placement were treated with bone grafts obtained from the mandibular symphysis. Complications encountered were minor and uneventful. Evaluation 4 months after surgery revealed minimal graft resorption, thus implant placement was possible in all potential sites. Advantages of the symphysis graft include easy access, availability of greater quantities of bone over other intraoral donor sites, low morbidity, no hospitalization, minimal discomfort, no alteration in ambulation, and no cutaneous scar. Compared with other bone regenerative methods for implant placement, a superior quality of bone was found and a shorter healing period is required. Results of this preliminary clinical investigation demonstrate that chin grafts offer a viable alternative for reconstruction of alveolar defects prior to dental implant placement.

A morphometric and biomechanic comparison of titanium implants inserted in rabbit cortical and cancellous bone.

Abstract: The removal torques for screw-shaped pure titanium implants inserted in rabbit tibia and the femoral part of the knee joint and the tissue response to these implants, as quantitated with light microscopic morphometry on ground sections, were compared after 6 weeks, 3 months, and 6 months The bone surrounding the femoral intra-articular implants was mostly cancellous, while cortical bone was formed around the tibial implants The torque needed to remove the intra-articular implants increased with time, but there was no such increase for the tibial implants At 6 weeks, significantly less torque was needed to remove the intra-articular implants in spite of the fact that significantly more bone was found in the threads of these implants as compared with the tibial implants When calculating the amount of bone in threads situated in the cortical and subchondral passage, more was found in the threads of the tibial implants, which corresponded to the higher removal torque Additional light microscopic observations on implants unscrewed after 12 months in rabbit tibia indicated that rupture occurred between the implant surface and calcified bone Findings indicate that the resistance to unscrewing is dependent on the amount of compact bone surrounding a titanium implant

Tissue integration of one-stage ITI implants: 3-year results of a longitudinal study with Hollow-Cylinder and Hollow-Screw implants.

Abstract: This study examined the tissue integration of one-stage, nonsubmerged ITI implants over a period of 3 years. Fifty-four implants were placed in 38 partially edentulous patients. Following healing (at least 3 months), all 54 implants were free of peri-implant infections and revealed no detectable mobility. Radiographs showed no signs of peri-implant radiolucencies, and the implants were in favorable positions for prosthetic restoration. Following incorporation of fixed partial dentures, patients were enrolled in a hygiene recall program with 3-month intervals and were examined once a year. Based on predefined criteria, each implant was classified as successful or failing. After the 3-year observation period, 51 of 53 implants (96.2%) were considered successfully integrated. (One patient with one implant dropped out of the study.) Two implants exhibited recurrent peri-implant infections and were classified as late failures. These results indicate that one-stage ITI implants can achieve successful tissue integration on a predictable basis and that it can be maintained over a period of at least 3 years.

Theoretical analysis of the fatigue life of fixture screws in osseointegrated dental implants.

Abstract: Metal fatigue failure of the gold screw used to retain a fixed prosthesis to Branemark osseointegrated fixtures/abutments has been analyzed theoretically. Mechanical engineering principles show the importance of appropriate preload being applied through the gold screw to the gold cylinder and abutment. The significance of the screw design and necessity of applying the correct torque to achieve a long fatigue life for the screw are also described. The consequence of misalignment of a gold cylinder to an abutment is discussed.

Failures and complications in 127 consecutively placed fixed partial prostheses supported by Brånemark implants: from prosthetic treatment to first annual checkup.

Abstract: Ninety-six partially edentulous maxillae and mandibles were consecutively treated with 127 freestanding fixed prostheses supported by 354 implants. The patients were followed for 1 year and the overall success rate was 98.6% for the examined implants. None of the inserted prostheses was lost during the observation period. The most commonly reported problems during the first year of function were related to loose gold screws and esthetic complaints, complications that were easily resolved. Furthermore, the total number of complications was low and was less than has been reported for routine full-arch fixed prostheses.

Comparison of impression techniques for a five-implant mandibular model.

Abstract: Production of an accurate dental cast framework that meets the implant objective of passive fit demands an understanding of potential processing errors. Working casts fabricated from impressions using two different transfer copings, as provided by a leading implant manufacturer, were investigated for differences in accuracy. A five-implant mandibular model was used to produce seven casts by both the indirect and direct transfer coping techniques. Comparison was made by using a dental cast framework fitted to the master cast. Differences in distances measured between each group and the master cast were analyzed to establish differences between methods. For the model used, the direct technique produced more accurate working casts. A concern for potential impression distortion given the specific clinical situation underscores the method of choice.

The use of titanium fixtures for intraoral anchorage to facilitate orthodontic tooth movement.

Abstract: The use of endosseous implants to facilitate orthodontic tooth movement has been periodically reported in the scientific literature for over 40 years. The predictable achievement of rigid bone-implant anchorage was first applied by Branemark in 1965. Using the osseointegration method, a prospective study was conducted involving seven adult patients who were treated with titanium implants used as rigid anchorage units. Orthodontic forces were directed off the implants to correct a variety of malocclusions. All 14 implants placed remained stable during the course of treatment with loading forces of 150 to 400 g. No significant complications occurred. Desirable occlusal and facial results were achieved in all cases. The results obtained over a 3-year period of treatment indicate that intraoral rigid anchorage in the absence of observed reciprocal action is possible.

The United States and Swedish experience with osseointegration and facial prostheses.

Abstract: A survey of experience treating patients with extraoral implants for facial prosthesis retention in 13 United States centers and in Sweden has been completed. Patients who have not received radiation for elimination of malignant disease can be treated with reasonably good expectations for long-term success. Reported success rates indicate that patients who have received radiation should be selected carefully and treated with caution, since overall success rates in this category are disappointingly low.

Titanium implants in irradiated tissue: benefits from hyperbaric oxygen.

Abstract: Since the introduction of osseointegrated titanium implants for bone-anchored facial and dental prostheses, an increasing number of irradiated patients are being treated with this technique. Although the number of patients who have had titanium implants after irradiation is limited, available statistics point to a tendency of a higher implant loss frequency as compared with nonirradiated patients. This review discusses factors behind deleterious tissue effects and implant failures from irradiation and points to possibilities to improve the surgical outcome with special reference to hyperbaric oxygen therapy.

Histomorphometry of bone apposition around three types of endosseous dental implants.

Abstract: Three different types of commercially available dental implants (Nobelpharma, IMZ, and Integral) were implanted in the edentulous mandibles of seven adult mongrel dogs. Twenty-one implants were harvested with block sections after 12 weeks and embedded in polymethyl methacrylate resin. Undecalcified sections were prepared with the sectioning-grinding technique. The percentage of bone contacting the implant surface was measured with a self-designed histomorphometry method using a millimeter grid in a stereomicroscope. The results demonstrated a significantly higher percentage of bone along the hydroxyapatite-coated implant than that seen with the titanium-surfaced implant types.

Comparison of impression techniques for a two-implant 15-degree divergent model.

Abstract: To consistently provide passively fitting implant superstructures, an understanding of the accuracy and precision of all phases of fabrication and connection is required. The initial phase of fabrication, ie, impression making and cast forming, was investigated in an earlier report for a mandibular five-implant model. The current study evaluates the accuracy of working casts produced from impressions using two different transfer copings in a 15-degree divergent two-implant posterior mandibular model. While the indirect method is less cumbersome to use, it was found to be less accurate in the prior study. The purpose of this study was to see if the direct method is more precise for this clinical situation. A transfer was deemed effective in producing experimental casts if distances between specified points on the cast agreed with the corresponding distances on the master cast. The absolute value of the difference in distances between experimental and master casts was compared for the two techniques (two-sample t tests). No significant differences were noted (P > .05), and the power of the tests ranged from 0.70 to 0.96 against the one-sided hypothesis that the direct method had a smaller mean absolute difference in distance than the indirect method. This suggests no clear advantage in using the direct method in similar clinical situations. Comparison of these findings to other impression accuracy studies is made.

A retrospective study of osseointegrated skin-penetrating titanium fixtures used for retaining facial prostheses.

Abstract: This investigation was conducted to evaluate osseointegrated skin-penetrating facial titanium implants used for anchoring facial prostheses over a 5-year period and to recommend guidelines for the use of osseointegrated implants in the restorative treatment of auricular and orbital defects. The total success rate for implant survival was 95.6% in the auricular defects and 67.2% in the orbital defects. Approximately 10% of the patients will have some skin problems, whereas the remaining 90% will have no or minimal problems. The possibility of achieving osseointegration around an orbital defect is not as good as in the mastoid process. Success criteria for the use of implants in the craniofacial region are given.

Endosseous implant placement immediately following dental extraction and alveoloplasty: preliminary report with 6-year follow-up.

Abstract: The philosophy of retaining natural teeth as long as possible for the preservation of alveolar bone has been a fundamental concept of dental treatment. With the introduction of predictable osseointegrated implant-supported prostheses, placement of an implant immediately after dental extraction can be considered. This paper discusses the technique of implant placement immediately following dental extraction. Clinical experience including 61 patients with follow-up of 1 to 6 years is reported.

A histomorphometric study of unthreaded hydroxyapatite-coated and titanium-coated implants in rabbit bone.

Abstract: Hydroxyapatite-coated and titanium-coated IMZ dental implants were investigated in an animal study. The implants were placed in the distal femurs of rabbits. Six months after placement, histomorphometric evaluation of the bone-to-implant contact was conducted. The hydroxyapatite-coated specimens demonstrated significantly more direct bone contact compared to the titanium-coated controls.

Combination of natural teeth and osseointegrated implants as prosthesis abutments: a 2-year longitudinal study.

Abstract: Twenty-three patients with Kennedy Class I mandibular dentition were supplied with prostheses in the posterior parts of the mandible On one side they were given a prosthesis supported by two implants (prosthesis Type I) and on the other side they received a prosthesis supported by one implant and one natural tooth (prosthesis Type II) Sixty-nine fixtures were inserted and 46 prostheses constructed Eight of the fixtures were lost during the observation period The failure rate of the implants was about the same in the two types of prostheses; five fixtures belonged to prostheses Type I (109%) and two fixtures belonged to prostheses Type II (87%), while one fixture was lost prior to loading From a theoretical point of view, the combination of a tooth and an osseointegrated implant should encounter problems with regard to the difference in bone anchorage and there should be a risk of biomechanical complications However, the results of this study did not indicate any disadvantages in connecting teeth and implants in the same restoration

A 3-year clinical study of Astra dental implants in the treatment of edentulous mandibles.

Abstract: A prospective study for the treatment of mandibular edentulism using the new Astra dental implant system was conducted on 54 patients The clinical performance of 310 implants was monitored over 3 years The survival rate was 100% for the prostheses and 981% for individual implants Four implants failed during the first 3 months after placement, one was retained as a "sleeper," and two more were removed because of persistent discomfort Both resorption and deposition of mandibular marginal bone were observed Bone changes from baseline to the end of the first year ranged from -04 to +10 mm (median 000), from the first to the third year from -08 to +06 mm (median 004), and over the 3 years ranged from -11 to +10 mm (median 001) No marked mean bone resorption was observed during the first year compared to the two following years A significant gain in marginal bone level was recorded in males, but in females the level was unchanged There were no serious inflammatory reactions in the surrounding soft tissues during the 3-year follow-up period

Heat distribution in bone during preparation of implant sites: heat analysis by real-time thermography.

Abstract: The purpose of this experiment was to observe and measure the distribution of heat to bones and the maximum temperature that developed when cutting bone with drills. Generation of heat that spread in the presence or absence of irrigation when drilling with IMZ, Branemark, and ITI implant (F type) drills was observed in the pig rib via thermography. Without irrigation, the condition of heat spread in each drill and bur differed according to bur shape and drilling site. Maximum heat temperature without irrigation was higher than that with irrigation for any IMZ, ITI, and Branemark drill.

Use of bovine osteogenic protein to promote rapid osseointegration of endosseous dental implants.

Abstract: An enriched bovine osteogenic protein preparation in combination with bone collagen matrix (osteogenic protein device) was used to effect new bone growth in extraction sites in the presence or absence of titanium dental implants. Incisor and canine teeth were extracted from each of three cynomolgus monkeys, and implants were inserted directly into the sockets without surgical site preparation. The osteogenic protein device induced new bone formation in close apposition to the titanium implants in all trials within 3 weeks. A lesser amount of new bone formation in both sets of control sites was limited to the bony socket walls and not closely apposed to the implant. These data show that the osteogenic protein device is capable of inducing new bone formation in tooth sockets within 3 weeks in the presence or absence of titanium implants. This is the first known demonstration of the therapeutic induction of bone formation in close apposition to metallic implants.

Fixture placement posterior to the mental foramen with transpositioning of the inferior alveolar nerve.

Abstract: The results of 10 fixture placement operations with transpositioning of the inferior alveolar nerve are presented. Nerve transpositioning increased the operating time, but with experience this time should be reduced. Neurosensory dysfunction of the inferior alveolar nerve was found in 7 of 10 operated sites 1 week after surgery. Six months postoperatively, altered sensation was still present in 2 patients. Nerve function was normal in all patients 1 year postoperatively. The stability of fixtures was satisfactory throughout the examination period and the procedure should prove useful in treatment of the resorbed mandible posterior to the mental foramina.

Patient satisfaction with overdentures supported by one-stage TPS implants.

Abstract: Sixty-four edentulous patients with severe conventional denture problems who had been treated with 218 one-stage titanium plasma sprayed (TPS) screw implants and new overdentures were clinically evaluated and questioned on their experiences with treatment up to 6 years after implant insertion. The results demonstrated that only seven of the implants had failed during this period, resulting in a success rate of 97%. Most of the patients (95%) were satisfied with their new overdentures, and almost all patients (98%) found that their new dentures fit comfortably. Only 3% of the patients treated would not recommend that others undergo similar treatment.

Effects of the Nd:YAG dental laser on plasma-sprayed and hydroxyapatite-coated titanium dental implants: surface alteration and attempted sterilization.

Abstract: The Nd:YAG dental laser has been recommended for a number of applications, including the decontamination or sterilization of surfaces of dental implants that are diseased or failing. The effects of laser irradiation in vitro (1) on the surface properties of plasma-sprayed titanium and plasma-sprayed hydroxyapatite-coated titanium dental implants, and (2) on the potential to sterilize those surfaces after contamination with spores of Bacillus subtilis have been examined. Surface effects were examined by scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction after laser irradiation at 0.3, 2.0, and 3.0 W using either contact or noncontact handpieces. Controls received no laser irradiation. Melting, loss of porosity, and other surface alterations were observed on both types of implants, even with the lowest power setting. For the sterilization study, both types of implants were first sterilized by exposure to ethylene oxide and then contaminated with spores of B subtilis. After laser irradiation, the implants were transferred to sterile growth medium and incubated. Laser irradiation did not sterilize either type of implant. The spore-contaminated implants in the control group were successfully sterilized with ethylene oxide.

Nasofacial prostheses supported by osseointegrated implants

Abstract: Surgical ablation in the nasofacial area may lead to defects that can be treated with maxillofacial prosthetic restorations retained by osseointegrated implants. When the prosthesis is large or impacted by masticatory or orbicularis muscle forces, the use of implants placed in available facial skeleton bone may be desirable. Available sites for implant placement in the facial skeleton are described, and a craniofacial site classification is suggested. Two examples of patients treated for nasofacial defects are presented.

Fixed implant rehabilitation for the edentulous maxilla.

Abstract: The edentulous maxilla presents, perhaps, the greatest challenge to implant therapy. The anatomic, esthetic, and functional demands for fixed reconstruction of the maxillary arch are affected by many variables, some of which are controllable by the surgeon and dentist. This paper describes those variables and offers suggestions for managing the controllable aspects of treatment while avoiding the uncontrollable ones. Suggestions for planning the surgical and prosthodontic phases of treatment are described.

Clinical parameters of evaluation during implant maintenance.

Abstract: This paper reviews investigations concerning the clinical parameters of evaluating dental implants during the maintenance phase of therapy. Clinical parameters that are discussed include mobility, gingival alterations, tissue movement, probing and attachment level measurements, bleeding upon probing, occlusion, and microbial monitoring. The role of implant radiology is discussed and encompasses radiographic interpretation, interval, and technique.

A new Brånemark single tooth abutment: handling and early clinical experiences.

Abstract: A new prosthetic concept, today available under the name CeraOne, for single tooth replacement with the Branemark system is described. This concept is characterized by a new design of the prefabricated components. A mechanical torque driver is used together with a gold screw and a special counter-torque device to ensure that the screw is tightened in an optimal manner to resist screw loosening and only transmit minor stress to the fixture interface. Another characteristic is the use of a prefabricated cap of sintered aluminum oxide as the basis for the ceramic crown. The crown is cemented to provide better esthetic possibilities even in situations of somewhat unfavorable fixture placement.

The immediate implant: a treatment alternative.

Abstract: The safety and efficacy of placing endosseous implants into the anterior mandible at the time of dental extractions with appropriate radical alveolectomies ("immediate implants") is reported. The results were compared to a control group of patients. The success of the immediate group was 92.7%; that of the control group was 98.1%. The difference in success rates was not significant at the P less than .05 level.

Three-dimensional force measurements on mandibular implants supporting overdentures.

Abstract: The purpose of this study was to determine masticatory and functional forces in three axes on mandibular implants supporting overdentures. Five edentulous test subjects were selected, each having two mandibular implants. Three-dimensional piezoelectric force transducers were mounted on the two-part ITI Bonefit implants and rigidly connected to the denture. Forces in vertical, lateromedial, and anteroposterior directions were measured by means of electrostatic plotter records. The test modalities were light tapping, grinding, maximal occlusal force, and chewing test food. Results showed that the five subjects developed similar stress patterns but quantitatively different occlusal and chewing forces. In all but one subject, reduced maximal occlusal force was found compared to dentate subjects and edentulous subjects with fixed partial prostheses supported by implants. The recordings of chewing cycles when eating test food resulted in very regular rhythmic strokes, similar to those of dentate subjects but with slightly reduced speed. All stress patterns showed that occlusal and chewing forces were mainly directed in vertical, medial, and anterior dimensions. The dominating component was vertical.